The atmosphere in literature is the way a writer uses setting, objects, or internal thoughts of characters to create emotion, mood, or experiences for the reader. And atmospheric tanka, a subgenre of tanka with its focus on atmosphere, intends to communicate first of all a feeling rather than an idea.
For example,
a dark
stand of cypress
where crows roost
watching me pass
night after night
Bright Stars, 3, 2014
Simon Hanson
This tanka deals with the eerie feeling associated with watchful night crows; This eerie feeling is effectively conveyed through well-chosen images/phrases: a "dark/stand" of cypress/ ... "crows" .../"watching" me pass/ "night after night."
In contrast with my tanka below:
a mob of crows
cawing in the wintry sky ...
a phalanx
of policemen
in riot gear
This tanka is about the intense, before-the-storm scene of rioting (as implied from a rectangular mass military formation, L3, of watchful riot police, Ls 4&5). The symbolically rich cawing crows in the wintry sky function like a foreshadowing of a bloody confrontation.
And
the rust-colored
twenty-foot-high border wall
draped with razor wire
stretches to the horizon ...
raven after raven croaking
This tanka tackles with the atmospheric border politics, manifested in the form of this seemingly endless border wall draped with razor wire, Ls 1-4, and the symbolically ominous, croaking ravens in L5 foreshadow evil, harm, or disaster.
Added: The following is a response tanka (not atmospheric one) to the "border wall"tanka:
the howling
of winter wind
through barbed wire ...
an old man stares
in piercing silence